For over thirty years it has been conventional to employ helical spring connectors of various sizes and lengths to connect sinuous spring bands to rails of furniture seat frames. In fact, most high quality sinuous seat spring assemblies in upholstered furniture manufactured during this period have incorporated helical spring connectors.
Helical spring connectors have shortcomings, however, which have been exacerbated by new technical developments and by the rising costs occasioned by the use of helicals, both in labor and materials, during the past few years. Specifically, the sinuous seat spring developments disclosed in Crosby U.S. Pat. No. 3,210,064, and Crosby et al. U.S. Pat. Nos. 3,388,904, and 3,525,514, produce greatly increased comfort through the development of leverage-amplification, torsioning and compression in the body of each band and moment-arm-induced-dropping of the band adjacent the back rail of the seat frame. These developments add to the cost of the seat spring assemblies but their luxury producing effects are so substantial that manufacturers have readily adopted them.
Against this background, although helical spring connectors do provide comfort input to the spring assemblies, their substantial and constantly rising cost now make their percentage contribution to the overall cost of the furniture piece far out of proportion to the amount of comfort input they provide; i.e., for their substantial expense they do not play a big enough role in the final seat spring performance. Furthermore, the inherent shortcomings of helical spring connectors, historically overlooked, such as noise sometimes caused by relative movement between the connector ends and the spring bands or rail clips, have magnified the manufacturers' distaste for such connectors in light of their other shortcomings.